Certamen was invented by Bonisagus and Tremere, as a peaceful means of resolving disputes between magi. Over the centuries, various specialized styles of Certamen have developed. Magi may learn a style with a season of instruction from a magus who knows that style. Magi may fight in modo ("in the style of") any style they know, and may change styles between rounds of each duel.

If a maga favors one style over all others, she may become an assectator (follower) of a style. Dueling as a follower of a given style allows a maga to use the most potent techniques of a style, but she may not change styles during a match. If a magus chooses to duel assectans (as a follower of a style), he must choose to do so at the beginning of the match, before first initiative is rolled, and may not change his style during the match. An assectator may choose to duel in modo for any match, and may change styles during the match, but does not gain the benefits of dueling assectans.

The default style is known as the style of the Gladiator, which has no special considerations, and functions exactly as described in the basic rules. Hermetic magi learn this style from their parens at the time their Gifts are Opened to the Hermetic Arts, and may fight in modo Gladiatoris.

The style of the Gladiatrix uses a chessboard as the setting for the duel. This style takes effect if both duelists agree beforehand. Any Hermetic magus may duel in modo Gladiatricis, as dueling in this fashion requires no special training. Those who are specially trained in this style may becomes assectatores Gladiatricium. Dueling assectans Gladiatricis enables a magus to force a match into a chessboard setting, and grants special capabilities to read his opponent's emotional reactions.

The style of the Andabata, or blind fighter, emphasizes savage attacks at the expense of defense. The Certamen setting churns and loses focus when a participant is dueling in modo Andabatae. Assectatores Andabatarum emphasize attacks without as much loss in defense.

The style of the Bestiarius, or beast fighter, is only available to magi with a Heartbeast. Dueling in modo Bestiarii draws on the strength of the Heartbeast, allowing the maga to substitute Corpus for Animal, or vice-versa, during a duel. Assectatores Bestiariorum may additionally draw on the Heartbeast to increase Resistance, when dueling assectans Bestiarii.

The Essedarius, or charioteer style, emphasizes flashy and potentially intimidating attacks that may cause an opponent to surrender. Dueling in modo Essedarii may cause an opponent to make a Brave check or surrender. Dueling assectans Essedarii enables even more intimidating attacks.

The style of the Hoplomachus, or hoplite, emphasizes defense over attack. Dueling in modo Hoplomachus sacrifices several advantages in return for increased defense. Dueling assectans Hoplomachus provides a greater defensive bonus.

The Laquearius, or snarer style, emphasizes techniques that bind the opponent's ritual, reducing its effectiveness. Dueling in modo Laquearii can reduce the opponent's defenses in the following round. Dueling assectans Laquearii can reduce the opponent's defense for the remainder of the duel.

The style of the Provocator, or challenger, emphasizes increased Resistance at the expense of Initiative. Dueling in modo Provocatoris provides a bonus to Resistance if the duelist gains the initiative but sacrifices it. Dueling assectans Provocatoris provides a bonus to Resistance without having to gain the initiative, but must accept a penalty to initiative.

The Retiarius, or fisherman style, emphasizes swift evasive attacks. Dueling in modo Retiarii allows a magus a chance to regain the initiative by sacrificing an otherwise successful attack. Dueling assectans Retiarii provides a bonus to initiative and enables the duelist to reclaim initiative if he loses it, by sacrificing an otherwise successful attack.

The style of the Saggitarius, or archer, emphasizes highly effective attacks that only inflict a single Fatigue level if successful, at the expense of defense. As no assectatores of this style are known to exist, duelists may only duel in modo Saggitarii.

The Scissor, or carver style, emphasizes slower, more powerful attacks. Dueling in modo Scissoris allows a duelist to forego an attack in one round, with a bonus to damage inflicted in the next round (assuming a successful attack). Dueling assectans Scissoris provides a greater damage bonus.

The style of the Velitus, or spearman, attempts to wear down the opponent's resistance early in the match. Dueling in modo Velitis allows a duelist to forego inflicting damage and instead reduce the opponent's Resistance in future rounds of the duel. Dueling assectans Velitis enables greater reduction to the opponent's Resistance.